Why can't we define destructors for non-handle classes?

I looked up documentation for destructors in Matlab, but it seems like they can only be defined for handle classes. Why is that? I can easily think of a use case for a non-handle class that needs a destructor:

classdef FileReader
    % FileReader very simple file reader

    properties
        fid
    end

    methods
        function obj = FileReader(file)
            obj.fid = fopen(file, 'r');
        end

        function varargout = read(obj,varargin)
            [varargout{1:nargout}] = obj.fread(obj.fid, varargin{:});
        end

        function delete(obj)
            fclose(obj.fid);
        end
    end
end

Answer 1

[Matthew Fall]

Never mind, I figured out how to do this with onCleanup:

classdef FileReader
    % FileReader very simple file reader

    properties
        fid
    end

    properties(Access=protected)
        cleanup
    end

    methods
        function obj = FileReader(file)
            obj.fid = fopen(file, 'r');
            obj.cleanup = onCleanup(@() obj.delete);
        end

        function varargout = read(obj,varargin)
            [varargout{1:nargout}] = fread(obj.fid, varargin{:});
        end

        function delete(obj)
            fclose(obj.fid);
            disp('file closed!')
        end
    end
end